It's a media device. That's all it's really is for.

Probably a way to squeeze profit out of Vita games and offer more Playatation content.

It's main attraction is for streaming PS4 games to a 2nd TV.

Not really hence why its selling low in Japan and will probably sell low here too

The price seems great but I believe you need a vita memory card which is just essh

No. You can't play two different games at the same time. From a PS4 to TV. The moving thing is what it does. The only way to do that is the separate streaming service.

Because why not?

Well, the last thing. You can stream the image another tv, so no need for unplugging your console each time. 

You can play some high acclaimed vita games on the big screen like Killzone, Persona 4, Soul Sacrifice. Netflix and other media apps. Cheap price.

You can play anything that can play on the Vita except for games that don't emphasize touch screen use.  The Playstation TV is the western name for Playstation Vita TV.  The Playstation Vita TV is the Playstation Vita except it's a consolized version.

The latter.

I would use it, for example if I want to keep playing PS4 while someone else is using the main TV.

It released in Japan, so they might as well give it a shot over here since Vita can't exactly sell much worse than it is currently.